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Dörwald, Miriam; Schick, Barbara; Maierl, Johann; Kenngott, Rebecca Anna-Maria (27. July 2018): The differentiation of the fetal bovine testis with focus on development of seminiferous cords and testicular cords. 32nd Congress of the European Association of Veterinary Anatomists, 25. - 28. Juli 2018, Hannover, Germany.
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Abstract

Introduction: Fetal testicular development correlates with functioning adult fertility. Only little information is available on the fetal differentiation of the bovine testis. Existing studies mostly concentrated on one single special aspect e.g. origin and migration of primordial germ cells. The objective of the present study is to investigate the formation and differentiation of the bovine testis combining various research methods like light microscopy, immunohistochemistry and electron microscopy. Materials and Methods: The investigation was performed on 48 bovine fetuses ranging from crown-rump- length (CRL) 1.4–94 cm. Tissue specimen were collected at the Munich abattoir and fixed in 3.7% phosphate-buffered formalin solution and Bouin’s solution. Serial sections (5 μm) were stained with Haematoxylin-Eosin (HE) and Masson-Goldner staining. Immunohistochemical investigations were performed using various antibodies (Anti-Vimentin, Anti-Keratin 8, Anti-Keratin 18, Anti-DDX4, Anti-Laminin). Results: At 3.6 cm CRL, the tunica albuginea is distinctly developed separating the single layered keratin-8- positive surface epithelium from the forming seminiferous cords. Therefore, from 3.6 cm onwards so called “seminiferous cords” surrounded by a Laminin positive basal membrane can be observed. Seminiferous cords show an elongated to round shape and contain germ cells as well as somatic cells in a loose arrangement. From CRL 17 cm onwards, so called “testicular cords” can be detected. They contain DDX4 positive germ cells with different size and morphology as well as basally localized Vimentin-positive pre-Sertoli cells collocated orderly as a string of pearls. Furthermore, the location of germ cells varies from basal to luminal and their morphology varies throughout different CRLs. Additionally, the rete testis shows a specific keratin expression pattern. Conclusion: In order to characterize germ cells and pre-Sertoli cells at different developmental stages investigations with further markers including Alkaline Phosphatase, Oct3/4 and S100 are crucial. Additionally, the formation of seminiferous cords, germ cells as well as somatic cells require an electron microscopical examination.